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Can Math Solve an Environmental Health Mystery?

May06

In November 1987, Dr. Dave Ozonoff, an expert in public health, decided to return to the passion of his youth.

After reading a book about chaos theory, he pulled his old multivariable calculus text book off the shelf and solved every end-of-the-chapter problem set. That day Ozonoff, who hadn’t touched a math book since he was in college, determined he would get his skills back by doing one hour of math every day. “I said, ‘Wow, I gotta learn this stuff, this is going to be important in biology’,” he recalls.

Despite a busy schedule as Chair Emeritus of the Department of Environmental Health at Boston University (BU), and his intense involvement in research, he has not missed his math exercises for a single day. “Christmas, New Year’s, Thanksgivings, birthdays, anniversaries… I had kidney stones, I was operated on twice, and even then I managed to somehow do it,” says Ozonoff, 65.

A great part of Ozonoff’s work has focused on cancer in small communities of Upper Cape Cod, where cancer rates are 25% higher than the rest of Massachusetts. With 20 years of research, his team proved that a product known as perchloroethylene (PCE), once used to line the interior of the water pipes, raised the risk of breast cancer in the area. But exposure to PCE did not account for all cancers. There had to be something else.

Now, Ozonoff thinks his mathematical training could help him solve the problem. He is using a part of mathematics called lattice theory to scan his data for new connections between cancer and environmental exposures. Lattice theory had been used in marketing to figure out if people buying chips tend to also buy beer, for instance. Ozonoff thinks he can use these data mining techniques to figure out which health symptoms go together when people are exposed to a toxic substance.

“It is a very new way of thinking of a very old idea,” says 31-year-old Al Ozonoff, assistant professor of biostatistics at BU and Dave Ozonoffs’s son. While his dad works on his mathematical models in an office on Albany Street, Al is two blocks away working on how statistics can be used to forecast pandemic outbreaks. Also a mathematics major in college, part of his work involves studying small clusters of disease similar to the ones his father researches. “We need as many different ways of thinking about it as possible,” he says.

The elder Ozonoff’s work on water contaminated with PCE and other chemicals has sparked action from federal and state governments to reduce people’s exposure to chemicals. His work on PCE in Cape Cod “has been an important contribution,” says Perry Cohn, a research scientist at the New Jersey Department of Health and Senior Services. Cohn says the evidence that PCE was related with cancer in Cape Cod helped his Department set appropriate levels of PCE in drinking water in New Jersey.

But PCE is only one piece of the puzzle in Cape Cod and Ozonoff is now trying to find new connections between disease and the environment. To do that, he is going through his data all over again, this time using his new mathematical tools. “What these new methods allow you to do is find the hidden pattern in the data,” says Ozonoff, who has included lattice theory exercises in his daily mathematical training. “I don’t have the discipline to do what he does,” says his son, who was seven years old when his father started his math routine. But despite his admiration, he thinks it is going to be a long way until his dad’s math produces results. “The challenging part is translating theory into practice.”

– Story by Nuño Dominguez

Posted by Joseph, under environment, mathematics, profile  |  Date: May 6, 2008
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